Storage of bromine



United States Patent 9 Claims. (c1. 23216) The present invention concerns a method for the torage of elementary bromine.

Because of its high corrosive effect on metals and metal alloys, bromine is conventionally stored and transported in glass or glass-lined containers, lead or leadlined containers or Monel (trade name for an alloy containing approximately 67% by weight of nickel, 28% by weight of copper and by weight of other elements, mainly iron and manganese) containers. These methods are not fully satisfactory. Thus, the conventionally used glass or lead containers or containers lined with either glass or lead are heavy so that a very substantial amount of dead weight has to be transported. The Monel containers against this are expensive.

So far it has not been possible to use stainless steel containers for the storage and transportation of bromine although such containers, if used, could have relatively thin walls and would, therefore, have the advantage of being comparatively light and thus constitute less dead weight for transportation. However, because of the high corrosive action of bromine on steel, such containers could so far not be used.

It is an object of the present invention to provide a method by which stainless steel containers can be used for the storage and transportation of elementary bromine.

The invention consists in a method for the storage of bromine wherein the bromine is introduced into a stainless steel container in admixture with a nitrogen oxide.

The stainless steel may be, for example, chromium steel, nickel steel or molybdenum steel. If desired, the stainless steel container may comprise lead fixtures.

For the purposes of the present invention various nitrogen oxides can be used such as NO, N 0, N0 N 0 and the like. It is also possible to use mixtures of two or more of these gases.

The quantity of nitrogen oxide may vary. In many cases it will be very small, e.g. below 0.1% by weight of the bromine. In other cases a larger quantity of nitrogen oxide may be desirable. For the introduction of nitrogen oxide into the bromine, it is possible, for example, to contact the bromine intimately with fuming nitric acid. After phase separation, if any, the excess nitric acid is removed and the remaining bromine contains the required amount of nitrogen oxide gases dissolved therein. Alternatively, the nitrogen oxide gas, e.g. N0 can be absorbed by bromine, by bubbling N0 gas through bromine.

Both nitric acid and bromine are known to be highly noxious for steel and it was therefore surprising to find that a solution of nitrogen oxides in elementary bromine is innocuous to stainless steel.

By the storage method according to the invention the above listed disadvantages of the conventional methods are overcome. In addition, the use of stainless steel has the advantage that owing to the good heat conductivity of the steel the bromine in the containers can easily be cooled if and when necessary. Moreover, when proceeding in accordance with the invention moist bromine can also be stored, which is impossible with Monel containers where the stored bromine has to be absolutely dry.

In some cases it may be advantageous to coat the stainless steel containers on the outside with a material resistant to bromine, e.g. lead or silver. In this manner the outside of the container is protected from bromine splashes during filling and emptying. Such splashes may be noxious to the uncoated container even Where the splashed bromine originally contained a nitrogen oxide, since once the bromine is splashed on the surface, the gaseous nitrogen oxide is liable to evaporate. Moreover, when the container is filled or emptied in places where bromine is produced or consumed, the splashed bromine may not contain any nitrogen oxide from the outset.

The invention is illustrated by the following examples to which it is not limited.

Example 1 Bromine, free from organic matter and hydrobromic acid, is intensively mixed with 1% by weight (calculated on bromine) of fuming nitric acid. The excess nitric acid is allowed to separate from the bromine and is removed whereafter the bromine contains about 0.06% N0 and is suitable for storage in stainless steel containers.

Example 2 Bromine, free from organic matter and hydrobromic acid, is intensively mixed with 0.5% by weight (calculated on bromine) of turning nitric acid. Without separating the bromine from the acid, the acid containing bromine can now be stored in stainless steel containers without causing any damage to the containers.

Example 3 Nitrogen-dioxide (N0 is introduced into bromine by bubbling NO -gas through the bromine. The bromine, treated in this way, can be stored in stainless steel containers without causing any damage.

We claim:

1. Method for the storage of bromine wherein the bromine is introduced into a stainless steel container in admixture with a nitrogen oxide.

2. The method according to claim 1, wherein the nitrogen oxide is introduced into the bromine by intimately mixing the bromine with fuming nitric acid.

3. The method according to claim 1, wherein nitrogen oxide is dissolved in the bromine by bubbling nitrogen oxide gas through the bromine.

4. The method according to claim 1, wherein the bromine is freed of any HBr prior to the introduction of nitrogen oxide.

5. The method according to claim 1, wherein the stainless steel container is fitted with lead fixtures.

6. The method according to claim 1, wherein the stainless steel container is coated on the outside with a material resistant to bromine.

7. The method according to claim 1, wherein the container is from a steel selected from the group of chr0- mium steel, nickel steel and molybdenum steel.

8. The method according to claim 7, wherein an excess of nitric acid is used and the excess acid is removed after phase separation.

9. The method according to claim 7, wherein a calculated amount of nitric acid is used so as to produce a bromine solution containing less than 0.1% by weight of nitrogen oxide dissolved in the bromine.

N 0 references cited.

MORRIS O. WOLK, Primary Examiner. B. S. RICHMAN, Assistant Examiner. 

1. METHOD FOR THE STORAGE OF BROMINE WHEREIN THE BROMINE IS INTRODUCED INTO A STAINLESS STEEL CONTAINER IN ADMIXTURE WITH A NITROGEN OXIDE.
 2. THE METHOD ACCORDING TO CLAIM 1, WHEREIN THE NITORGEN OXIDE IS INTRODUCED INTO THE BROMINE BY INTIMATELY MIXING THE BROMINE WITH FUMING NITRIC ACID. 